(a) Field of the Invention
The present invention concerns a control device for controlling the movement of a pickup arm of a phonograph record player, a video disc player and the like. More particularly, the present invention pertains to a control device of the type described for automatically bringing, for example, a pickup arm up to a required position above a record disc of a record player, or for automatically lifting up the pickup arm from the surface of the record disc upon competion of the playing of the disc and for causing this uplifted pickup arm to return to the predetermined rest position of the pickup arm.
(B) Brief Description of the Prior Art
There has been proposed a number of devices aimed for automatically controlling the movement of a pickup arm of a record player or the like. However, such a known control device which is adaptable for use in a record player of a high-class standard or in a record player designed for the ues of professional persons has not been successfully produced until now for the reasons as will be described below.
It can be said, in general, that a control device designed to perform an automatic control of the pickup arm movement requires means for detecting the position of the pickup arm. With known control devices, however, the position-detecting means usually is constructed of a single or plural switch means and for example a movable lever which is fixed to the supporting shaft of a supporting means of the pickup arm for horizontal swinging movement jointly with the pickup arm. In such prior art arrangement, the lever is designed to move along together with the pickup arm and to engage the switch means when the pickup arm arrives at a predetermined position, causing the switch means to perform a changeover of connection for automatic control of the pickup arm movement. It should be noted, accordingly, the reaction force of such a changeover action of the switch means tends to be applied to the pickup arm via the movable lever and also the supporting means, with the result that the free movement of the pickup arm is hampered. And also, the provision of the movable lever on the supporting shaft will give an adverse effect on the performance characteristics of the pickup arm. Furthermore, it is impossible to provide such movable lever in a high-class or professional type record player, since the pickup arm supporting means of the record player of such type has not a shaft portion which is arranged to swing in accordance with the movement of the pickup arm. This is the most important reason why the prior art control device can not be utilized for the control of a high-class record player.
Moreover, in general, means for returning the pickup arm from an arbitrary position to the rest position has to be provided on the control device to conduct the automatic control function of the pickup movement. To the prior art, however, the returning operation is usually performed by means of a motor exclusively provided for this returning of the pickup arm, and this motor is arranged to be coupled, via a transmission mechanism, to the supporting shaft which is movable jointly with the pickup arm. It should also be noted that in a high class record player is provided no supporting shaft arranged to move with the pickup arm. In such high class record player, the pickup arm is usually supported by the use of a supporting means of the so-called one-point supporting system or the so-called four-point gimbal supporting system. Therefore, the prior art arrangement is not suitable for use in a high class record player. Moreover, a known control device arrangement will, even if applied to the consumer-type record player which usually adopts a relatively simple supporting means such as the so-called two-point supporting system, give a much undesirable effect upon such performance characteristics of the pickup arm as the lower resonance frequency, the lateral balance, the inside force, the tracking error and the efficiency of inertia.
For the reasons as described above, the control device of the prior art has not been adopted in high-class record players.
On the other hand, in case a pickup arm is directly operated manually, there tends to occur accidents such that the pickup cartridge which is attached to the foremost end of the pickup arm is damaged and/or the disc record surface could be injured, through some mis-handling of the pickup arm or for like reasons. Moreover, the handling of the pickup arm is complicated and troublesome.
As such, there has been an increasing strong demand for the development of an improved control device for automatically or remotely controlling the movement of a pickup arm, which device not causing ill effects on the performance of the pickup arm.